1. Field of the Invention
The present invention relates to the technology of performing CT imaging with an X-ray.
2. Description of the Background Art
In the medical field or the like, X-ray CT imaging is conventionally performed, in which an X-ray is radiated to an object to collect projection data, and then the obtained projection data is recreated on a computer, to thereby generate computerized tomography images (such as a CT tomographic image and a volume rendering image).
In such X-ray imaging, a cone-shaped X-ray (X-ray cone beam) is radiated to an object from an X-ray generator while the X-ray generator and an X-ray detector are rotated about an object with the object being located between the X-ray generator and the X-ray detector. Then, X-ray detection results (projection data) obtained by the X-ray detector are collected, to thereby recreate three-dimensional data. For example, Japanese Patent No. 3378401 discloses the apparatus that performs X-ray CT imaging as described above.
Japanese Patent No. 3378401 discloses the technology of performing, by an X-ray imaging apparatus, CT imaging of a wider range with a small X-ray detection surface by means of offset scan in which imaging is performed while constantly irradiating a part of an object by displacing the position irradiated with an X-ray cone beam from the center of the object.
In the X-ray imaging apparatus of Japanese Patent No. 3378401, however, a CT image area is circular (also oval), and thus in a case where an area of interest desired to be imaged by an operator is not circular, the areas besides the area of interest are also subjected to X-ray irradiation. This may increase an X-ray exposure amount unnecessarily.